Category: Sysadmin

System administration is a special are of IT. It also has a special place in my heart. It is an interesting mixture of all the other disciplines, both common across the whole industry, and at the same time unique for each person, company, and geographical location. When I have something to say or share about system administration, I use this category.

HAProxy SNI

“HAProxy SNI” is pure gold! If you want to have a load balancer for HTTPS traffic, without managing SSL certificates on the said load balancer, there is a way to do so.

The approach is utilizing the Server Name Indication (SNI) extension to the TLS protocol.  I knew about it and I was already using it on the web server side, but it didn’t occur to me that it’ll be utilized on the load balancer.  Here’s the configuration bit:

frontend https *:443
  description Incoming traffic to port 443
  mode tcp
  tcp-request inspect-delay 5s
  tcp-request content accept if { req_ssl_hello_type 1 }
  use_backend backend-ssl-foobar if { req_ssl_sni -i foobar.com }
  use_backend backend-ssl-example if { req_ssl_sni -i example.com }
  default_backend backend-ssl-default

The above will make HAProxy listen on port 443, and then send all traffic for foobar.com to one backend, all traffic for example.com to another backend, and the rest to the third, default backend.

Boostnote – Open Source note-taking app for programmers

Boostnote is yet another alternative for taking notes.   This one is an Open Source and is built for developers.  Some of the features – Markdown support, search, cross-platform, works offline.

There is also Boostnote Team edition for, you know, teams.

BitBucket Pipelines improved support for Docker

Here are some exciting news from the BitBucket Pipelines blog: Bitbucket Pipelines now supports building Docker images, and service containers for database testing.

We developed Pipelines to enable teams to test and deploy software faster, using Docker containers to manage their build environment. Now we’re adding advanced Docker support – building Docker images, and Service containers for database testing.

Writing systemd Units

Vidar Hokstad explains what systemd units are and how to write them.  Very useful for that day when I will stop hating systemd and will try to embrace it.

Systemd has become the defacto new standard init for Linux-based systems. While not everyone has made the switch yet, pretty much all the major distros have made the decision to switch.

For most people this has not meant all that much yet, other than a lot of controversy. Systemd has built in SysV init system compatibility, and so it’s possible to avoid dealing with it quite well.

But there is much to be gained from picking up some basics. Systemd is very poweful.

I’m not going to deal with the basics of interacting with systemd as that’s well covered elsewhere. You can find a number of basic tips and tricks here.

Instead I want to talk about how to write systemd units.